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Introduction: An appropriate supply of ammonium (NH4+) in addition to nitrate (NO3-) can greatly improve plant growth and promote maize productivity. However, knowledge gaps exist regarding the mechanisms by which different nitrogen (N) fertilizer sources affect the enzymatic activity of nitrogen metabolism and non-structural carbohydrates during the post-anthesis period. Methods: A field experiment across 3-year was carried out to explore the effects of four nitrateammonium ratio (NO3-/NH4+ = 1:0 (N1), 1:1 (N2), 1:3 (N3), and 3:1 (N4)) on postanthesis dry matter (DM) and N accumulation, partitioning, transportation, and grain yield in maize. Results: NO3-/NH4+ ratio with 3:1 improved the enzymatic activity of N metabolism and non-structural carbohydrate accumulation, which strongly promoted the transfer of DM and N in vegetative organs to reproductive organs and improved the pre-anthesis DM and nitrogen translocation efficiency. The enzymatic activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamine oxoglutarate aminotransferase, and non-structural carbohydrate accumulation under N4 treatment were increased by 9.30%-32.82%, 13.19%-37.94%, 4.11%-16.00%, 11.19%-30.82%, and 14.89%-31.71% compared with the other treatments. Mixed NO3--N and NH4+-N increased the total DM accumulation at the anthesis and maturity stages, simultaneously decreasing the DM partitioning of stem, increasing total DM, DM translocation efficiency (DMtE), and contribution of pre-anthesis assimilates to the grain (CAPG) in 2015 and 2017, promoting the transfer of DM from stem to grain. Furthermore, the grain yield increased by 3.31%-9.94% (2015), 68.6%-26.30% (2016), and 8.292%-36.08% (2017) under the N4 treatment compared to the N1, N2, and N3 treatments. Conclusion: The study showed that a NO3-/NH4+ ratio of 3:1 is recommended for high-yield and sustainable maize management strategies in Northwestern China.
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To optimize the effects of nitrate (NO3--N) to ammonium (NH4+-N) ratios on water consumption characteristics, grain yield and water use efficiency (WUE) of maize under full film mulching on double ridges, a field experiment was conducted at semi-arid Loess Plateau of Gansu Province, China during 2015 to 2017 cropping seasons. The treatments with different ratios of NO3--N to NH4+-N included: N1 (1:0), N2 (1:1), N3 (1:3) and N4 (3:1). The results showed that different NO3--N/NH4+-N ratios had significant impacts on soil water storage in 0-200 cm soil layer. Treatment N3 had the lowest soil water storage. Treatment N4 significantly increased total water consumption by 2.9%, 1.9% and 0.9% in 2015, and 2.3%, 1.4%, and 2.2% in 2017, compared with N1, N2 and N3 treatments, respectively. Compared with the other treatments, treatment N4 increased grain yield by 3.3%-9.9%, 3.5%-24.2% and 8.3%-36.1% and improved WUE by 1.6%-6.8%, 4.9%-21.8%, and 6.6%-32.9% in 2015, 2016 and 2017, respectively. Treatment N4 had the highest partial productivity of nitrogen fertilizer, followed by N2, N3 and N1, respectively. We recommended treatment N4 as the best nitrate and ammonium ratio to improve water use efficiency, N partial productivity, and grain yield of maize in arid and semi-arid Loess Plateau.
Asunto(s)
Nitrógeno , Zea mays , Agricultura , China , Ingestión de Líquidos , Suelo , AguaRESUMEN
Compared with intact plants, decapitation did not cause increase in dry weight of tobacco plant and in potassium accumulation 8 weeks after the treatment. In intact plants, about 1/3 of assimilation and potassium were transported into the top, and only about 1/3 of those deposited in the leaves. Decapitation resulted in about 1/2 of assimilation and potassium distributing in the leaves, so it was more effective. Application of NAA on the stump of the stem did not influence leaves yields, but accumulation of potassium in the upper and middle leaves was enhanced.
